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At least 199 records · Page 11Linked to original sources
PubMed1980

A program library for computing the parameters of linear compartment models in pharmacokinetics.

A program library is presented with which explicit solutions of linear compartment models can be fitted to pharmacokinetic experimental data. Use is made of the fact that transport constants can be calculated from the numberical solution of such a problem without ambiguity. The non-linear regression is carried out using the Powell-method. A report of our experience with, e.g. choice of objective function, lag-time, accuracy of the numerical solution is included.

Computers↗
PubMed1988

Identification and rejection of outliers in enzyme kinetics.

A program (AICOUT) for the correct choice of the experimental value and weight for replicate enzyme kinetic determinations is given. It is based on the method of identification of outliers proposed by Kitagawa (Technometrics, 21 (1979) 193-199). The program is written in BASIC and FORTRAN77. The FORTRAN77 version of AICOUT program coupled to a FORTRAN77 version of the non-linear regression program previously published by Canela (Int J Biomed Comput, 15 (1984) 121-130) is given. This joint program leads to an improvement of precision and confidence in the estimated parameters when the suitable strategy is used. This strategy is as follows: (i) the experimental points are selected, (ii) several replicates of each point are performed, (iii) data are analyzed and outliers are rejected, (iv) normal or biweighted regression is carried out.

Algorithms↗
PubMed1991

Gas chromatographic system for the identification of halogenated pesticides by retention indices using n-alkanes as standards.

A gas chromatographic system for the evaluation of linear temperature-programmed retention indices allowing n-alkanes to be adopted as the reference retention markers for any type of analyte, irrespective of the atoms present in their molecules, is described. It is based on the simultaneous use of two different detectors (a flame ionization detector and a specific detector suitable for the sample components), both connected (in parallel) to the same column outlet. The performance of this system has been tested by measuring the retention indices of fifteen chlorinated pesticides under conditions of linear programming temperature, by adopting an electron-capture detector as the specific detector. The reliability of the retention indices thus determined has been proven by verifying that they can be reproduced under different chromatographic conditions.

Alkanes↗
PubMed1989

BOOMER, a simulation and modeling program for pharmacokinetic and pharmacodynamic data analysis.

BOOMER is an improved version of an earlier non-linear regression program, MULTI-FORTE. Rather than the user writing a FORTRAN subroutine, models are defined by means of the parameters which make up the model. Models based on differential equations are specified by means of zero-order, first-order, or Michaelis-Menten-type rate constants. Doses (in units of mass) are translated into the usually observed concentration units by a reciprocal volume parameter. Integrated equation models are specified in terms of baseline terms, exponential terms, or the emax function with slope term as described by the Hill equation. Time points can be specified as parameters to specify dose times, infusion start/stop times, or lag times. With careful selection of parameters quite complex models can be specified. The user has a choice of differential equation solvers and fitting algorithms.

Computer Simulation↗
PubMed1986

MULTI-FORTE, a microcomputer program for modelling and simulation of pharmacokinetic data.

MULTI-FORTE is an expanded version of the MULTI non-linear fitting programs written by Yamaoka et al. The functions of the three original programs (including Gauss-Newton and Simplex fitting algorithms) have been combined and translated into FORTRAN 77 on the Macintosh computer for both speed and convenience. Models can be described in integrated equation form or as a system of differential equations. Bayesian estimation is also available. Improved numerical integration routines have been added including methods suitable for systems of 'stiff' differential equations (Fehlberg's 4/5 Runge-Kutta method and Gear's DIFSUB subroutine). MULTI-FORTE is a user-friendly program taking data from keyboard or disk file to produce output on screen, printer, or disk file in tables or printer-type plots.

Computer Simulation↗
PubMed1995

A PC program for unbiased and predictive linear and quadratic discriminant analysis.

Discriminant analysis plays an important role in biological and medical research. The most popular methods of discrimination in practical applications are parametric methods like linear and quadratic discriminant analysis. However, there exist modifications of these approaches, namely unbiased and predictive discriminant analysis, which lead to reduced error rates in certain situations. In this paper a menu-driven, user-friendly PC program written in Borland Pascal 7.0 is introduced which performs unbiased and predictive linear and quadratic discriminant analysis.

Bias↗
PubMed1979

A kinetic method for glucose that is insensitive to variations in temperature and enzyme activity.

We have adapted for glucose determination a new approach to kinetic analyses [Anal. Chem. 50, 1611 (1978)]; it is 50-fold less dependent upon some experimental variables than is a more conventional rate method. Modification of a commercially available hexokinase/glucose-6-phosphate dehydrogenase reagent system for glucose provides that the rate of production of NADH be first-order in total glucose concentration within about 30 s after sample and reagent are mixed. In the kinetic method, absorbance vs. time data recorded after 30 s and a multiple-linear-regression program are used to compute the absorbance change that would occur if the reaction were monitored to completion. Results demonstrate a linear relationship between glucose concentration and computed absorbance change. Application of the method to 51 human sera without rigorous control of either temperature or reagent composition yielded a regression equation of y = 1.01x -0.3 when kinetic results (y) were compared with equilibrium results (x) for the same samples analyzed in a hospital laboratory.

Blood Glucose↗
PubMed1980

A minicomputer program for automatic saccade detection and linear analysis of eye movement systems using sine wave stimulus.

A FORTRAN IV program is described, which may be run interactively or in batch and which allows a user to obtain the frequency response amplitude ratio and phase resulting from the linear analysis of an eye movement system using sine wave stimuli. The response (eye position) signal may contain components contributed by the saccadic eye movements. The program can digitize analog signals and store data on a magnetic tape. With the aid of digital filters, the program can detect saccades without requiring any input parameters from the user. The program interpolates the saccade interval using a method of least square curve fitting with a sine wave. The interpolation is relatively noise immune and works well regardless of the stimulus frequencies and the width of a saccade interval. Moreover, the program can handle long duration of signals such as 90 min of data which covers about 5 cycles of a 0.001 Hz sine wave signal. Sample runs for the cases of 0.001 and 0.1 Hz are given. The resident driver and the overlayable segments of the program have been implemented on a DEC (Digital Equipment Corp.) LAB-11 minicomputer (PDP 11/20).

Animals↗
PubMed1995

Identification of human gene structure using linear discriminant functions and dynamic programming.

Development of advanced technique to identify gene structure is one of the main challenges of the Human Genome Project. Discriminant analysis was applied to the construction of recognition functions for various components of gene structure. Linear discriminant functions for splice sites, 5'-coding, internal exon, and 3'-coding region recognition have been developed. A gene structure prediction system FGENE has been developed based on the exon recognition functions. We compute a graph of mutual compatibility of different exons and present a gene structure models as paths of this directed acyclic graph. For an optimal model selection we apply a variant of dynamic programming algorithm to search for the path in the graph with the maximal value of the corresponding discriminant functions. Prediction by FGENE for 185 complete human gene sequences has 81% exact exon recognition accuracy and 91% accuracy at the level of individual exon nucleotides with the correlation coefficient (C) equals 0.90. Testing FGENE on 35 genes not used in the development of discriminant functions shows 71% accuracy of exact exon prediction and 89% at the nucleotide level (C = 0.86). FGENE compares very favorably with the other programs currently used to predict protein-coding regions. Analysis of uncharacterized human sequences based on our methods for splice site (HSPL, RNASPL), internal exons (HEXON), all type of exons (FEXH) and human (FGENEH) and bacterial (CDSB) gene structure prediction and recognition of human and bacterial sequences (HBR) (to test a library for E. coli contamination) is available through the University of Houston, Weizmann Institute of Science network server and a WWW page of the Human Genome Center at Baylor College of Medicine.

Algorithms↗
PubMedDate not supplied

Symbolic programs for structural identification of linear pharmacokinetic systems.

Most parameter estimation techniques implicitly assume that it is possible to determine the parameters of the system uniquely if there were no noise in the output. In practice, this is not always the case. Whether or not this assumption is true for a given input-output experiment is the problem of structural identification. Two programs utilizing symbolic matrix calculus are presented which aid in solving this problem for linear systems. Pharmacokinetic examples are given.

Computers↗
PubMed1982

A computer program for the analysis of structural identifiability and equivalence of linear compartmental models.

A FORTRAN program based on the sufficient and necessary algebraic condition for structural identifiability is presented. In the case of an unidentifiable model the program generates all identifiable submodels that are structurally equivalent to the original model in the given input--output experiment. The parametrization vector of the model may include first-order and zero-order transport rate coefficients, unknown distribution volumes and initial conditions, as well as unknown elements of input and output matrices. Any a priori constraint imposed upon the parameters may be taken into account. An attempt is made to reduce input data requirements preserving generality of the program.

Computers↗